Details
| Original language | English |
|---|---|
| Article number | 647 |
| Journal | CATALYSTS |
| Volume | 8 |
| Issue number | 12 |
| Early online date | 10 Dec 2018 |
| Publication status | Published - Dec 2018 |
Abstract
Mixtures and composites of Ag/Ag 2 O and TiO 2 (P25) with varying mass ratios of Ag/Ag 2 O were prepared, employing two methods. Mechanical mixtures (TM) were obtained by the sonication of a suspension containing TiO 2 and Ag/Ag 2 O. Composites (TC) were prepared by a precipitation method employing TiO 2 and AgNO 3 . Powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of Ag(0) and Ag 2 O. The activity of the materials was determined employing methylene blue (MB) as the probe compound. Bleaching of MB was observed in the presence of all materials. The bleaching rate was found to increase with increasing amounts of TiO 2 under UV/vis light. In contrast, the MB bleaching rate decreased with increasing TiO 2 content upon visible light illumination. XRD and XPS data indicate that Ag 2 O acts as an electron acceptor in the light-induced reaction of MB and is transformed by reduction of Ag + , yielding Ag(0). As a second light-induced reaction, the evolution of molecular hydrogen from aqueous methanol was investigated. Significant H 2 evolution rates were only determined in the presence of materials containing more than 50 mass% of TiO 2 . The experimental results suggest that Ag/Ag 2 O is not stable under the experimental conditions. Therefore, to address Ag/Ag 2 O as a (photo)catalytically active material does not seem appropriate.
Keywords
- Hydrogen evolution, In situ deposition, Mechanical mixture, Photocatalysis, Silver(II) oxide, Titanium dioxide
ASJC Scopus subject areas
- Chemical Engineering(all)
- Catalysis
- Chemistry(all)
- Physical and Theoretical Chemistry
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In: CATALYSTS, Vol. 8, No. 12, 647, 12.2018.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Ag/Ag2O as a Co-Catalyst in TiO2 Photocatalysis: Effect of the Co-Catalyst/Photocatalyst Mass Ratio
AU - Akel, Soukaina
AU - Dillert, Ralf
AU - Balayeva, Narmina O.
AU - Boughaled, Redouan
AU - Koch, Julian
AU - Azzouzi, Mohammed El
AU - Bahnemann, Detlef Bahnemann Detlef
PY - 2018/12
Y1 - 2018/12
N2 - Mixtures and composites of Ag/Ag 2 O and TiO 2 (P25) with varying mass ratios of Ag/Ag 2 O were prepared, employing two methods. Mechanical mixtures (TM) were obtained by the sonication of a suspension containing TiO 2 and Ag/Ag 2 O. Composites (TC) were prepared by a precipitation method employing TiO 2 and AgNO 3 . Powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of Ag(0) and Ag 2 O. The activity of the materials was determined employing methylene blue (MB) as the probe compound. Bleaching of MB was observed in the presence of all materials. The bleaching rate was found to increase with increasing amounts of TiO 2 under UV/vis light. In contrast, the MB bleaching rate decreased with increasing TiO 2 content upon visible light illumination. XRD and XPS data indicate that Ag 2 O acts as an electron acceptor in the light-induced reaction of MB and is transformed by reduction of Ag + , yielding Ag(0). As a second light-induced reaction, the evolution of molecular hydrogen from aqueous methanol was investigated. Significant H 2 evolution rates were only determined in the presence of materials containing more than 50 mass% of TiO 2 . The experimental results suggest that Ag/Ag 2 O is not stable under the experimental conditions. Therefore, to address Ag/Ag 2 O as a (photo)catalytically active material does not seem appropriate.
AB - Mixtures and composites of Ag/Ag 2 O and TiO 2 (P25) with varying mass ratios of Ag/Ag 2 O were prepared, employing two methods. Mechanical mixtures (TM) were obtained by the sonication of a suspension containing TiO 2 and Ag/Ag 2 O. Composites (TC) were prepared by a precipitation method employing TiO 2 and AgNO 3 . Powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of Ag(0) and Ag 2 O. The activity of the materials was determined employing methylene blue (MB) as the probe compound. Bleaching of MB was observed in the presence of all materials. The bleaching rate was found to increase with increasing amounts of TiO 2 under UV/vis light. In contrast, the MB bleaching rate decreased with increasing TiO 2 content upon visible light illumination. XRD and XPS data indicate that Ag 2 O acts as an electron acceptor in the light-induced reaction of MB and is transformed by reduction of Ag + , yielding Ag(0). As a second light-induced reaction, the evolution of molecular hydrogen from aqueous methanol was investigated. Significant H 2 evolution rates were only determined in the presence of materials containing more than 50 mass% of TiO 2 . The experimental results suggest that Ag/Ag 2 O is not stable under the experimental conditions. Therefore, to address Ag/Ag 2 O as a (photo)catalytically active material does not seem appropriate.
KW - Hydrogen evolution
KW - In situ deposition
KW - Mechanical mixture
KW - Photocatalysis
KW - Silver(II) oxide
KW - Titanium dioxide
UR - http://www.scopus.com/inward/record.url?scp=85060036665&partnerID=8YFLogxK
U2 - 10.3390/catal8120647
DO - 10.3390/catal8120647
M3 - Article
VL - 8
JO - CATALYSTS
JF - CATALYSTS
SN - 2073-4344
IS - 12
M1 - 647
ER -